Halophilanema prolata n. gen., n. sp. (Nematoda: Allantonematidae), a parasite of the intertidal bug, Saldula laticollis (Reuter)(Hemiptera: Saldidae) on the Oregon coast

This is the publisher’s final pdf. The published article is copyrighted by BioMed Central and can be found at: http://www.biomedcentral.com/.Background: It is rare to find terrestrial nematode lineages parasitizing arthropods inhabiting the intertidal or\ud littoral zone of the oceans. During an ecological study along the Oregon dunes, an allantonematid nematode\ud (Tylenchomorpha: Allantonematidae) was discovered parasitizing the intertidal shore bug, Saldula laticollis (Reuter)\ud (Hemiptera: Saldidae). This shore bug is adapted to an intertidal environment and can survive short periods of\ud submergence during high tides. The present study describes the nematode parasite and discusses aspects of its\ud development, ecology and evolution.\ud Methods: Adults and last instar nymphs of S. laticollis (Hemiptera: Saldidae) were collected from the high intertidal\ud zone among clumps of Juncus L. (Juncaceae) plants at Waldport, Oregon on October 3, 2011. The bugs were\ud dissected in 1% saline solution and the nematodes killed in 1% Ringers solution and immediately fixed in 5%\ud formalin (at 20°C). Third stage juveniles removed from infected hosts were maintained in 1% saline solution until\ud they matured to the adult stage, molted and mated.\ud Results: Halophilanema prolata n. gen., n. sp. (Nematoda: Allantonematidae) is described from last instar nymphs\ud and adults of the intertidal bug, Saldula laticollis on the Oregon coast. The new genus can be distinguished from\ud other genera in the Allantonematidae by a stylet lacking basal knobs in both sexes, an excretory pore located\ud behind the nerve ring, ribbed spicules, a gubernaculum, the absence of a bursa and the elongate-tubular shape of\ud the ovoviviparous parasitic females. Studies of the organogenesis of Halophilanema showed development to third\ud stage juveniles in the uterus of parasitic females. Maturation to the free-living adults and mating occurred in the\ud environment. The incidence of infection of S. laticollis ranged from 0% to 85% depending on the microhabitat in\ud the intertidal zone.\ud Conclusions: Based on the habitat and morphological characters, it is proposed that Halophilanema adapted a\ud parasitic existence fairly recently, evolutionarily speaking. It was probably a free-living intertidal or shore nematode\ud that fed on microorganisms, especially fungi, in the intertidal habitat and became parasitic after saldids entered the\ud environment. Halophilanema represents the first described nematode parasite of an intertidal insect

Regulation of Alr1 Mg Transporter Activity by Intracellular Magnesium

Mg homeostasis is critical to eukaryotic cells, but the contribution of Mg transporter activity to homeostasis is not fully understood. In yeast, Mg uptake is primarily mediated by the Alr1 transporter, which also allows low affinity uptake of other divalent cations such as Ni2+, Mn2+, Zn2+ and Co2+. Using Ni2+ uptake to assay Alr1 activity, we observed approximately nine-fold more activity under Mg-deficient conditions. The mnr2 mutation, which is thought to block release of vacuolar Mg stores, was associated with increased Alr1 activity, suggesting Alr1 was regulated by intracellular Mg supply. Consistent with a previous report of the regulation of Alr1 expression by Mg supply, Mg deficiency and the mnr2 mutation both increased the accumulation of a carboxy-terminal epitope-tagged version of the Alr1 protein (Alr1-HA). However, Mg supply had little effect on ALR1 promoter activity or mRNA levels. In addition, while Mg deficiency caused a seven-fold increase in Alr1-HA accumulation, the N-terminally tagged and untagged Alr1 proteins increased less than two-fold. These observations argue that the Mg-dependent accumulation of the C-terminal epitope-tagged protein was primarily an artifact of its modification. Plasma membrane localization of YFP-tagged Alr1 was also unaffected by Mg supply, indicating that a change in Alr1 location did not explain the increased activity we observed. We conclude that variation in Alr1 protein accumulation or location does not make a substantial contribution to its regulation by Mg supply, suggesting Alr1 activity is directly regulated via as yet unknown mechanisms